When applying Iron Sulfate to the soil, we highly recommend using a soil analysis to apply the correct amount specific to your soil. Over application can lead to excesses and even possible toxicity.
Apply the following per 100L of soil volume
Low to medium deficiency: 1.5ml - 8ml per 100L of soil volume.
Medium to high deficiency: 8ml - 16ml per 100L of soil volume.
NB: Please note these dilutions are not ml per Litre, but rather the total amount to be added to 100L of soil volume. For example; if you had a 100L pot of soil with a low deficiency of Iron, you would add 1.5ml of Iron Sulfate to water, then evenly apply this to the soil in the pot.
We recommend using this with Forest Roots Fulvic Acid for increased absorption and uptake by plants.